I'm thinking of recycling some filament from a couple of recently failed prints. I can reuse them in the future for basic prototypes, so I'm not concerned with whatever weird mixture of colors come out (they are of a few different colors).

The thing is, I have both PLA and ABS, in small quantities. I originally intended to simply use each one separately, but it occurred to me that they could be mixed.

If I recycle PLA and ABS together into one strand of filament, will there be any negative side effects (e.g. reduced strength)?

4 Answers
4

This is not a good idea. Both filaments have different melting points, that of ABS being much higher than that of PLA. To melt the ABS you have to heat the plastic to the point where the PLA starts to degrade.

$\begingroup$While I agree it's not a good idea, I don't think it's completely improbable. I've had success in the past with printing ABS and PLA (separately) between 220-225C with no issues printing. In the end, if you combined the two materials, you would need to relearn what extrusion temperatures work for the new material. You'll probably lose a lot of the strength of ABS and rigidity in the PLA by combining them, however it would be a nice cheap alternative if you have a bunch of scrap material and need a simple knick-knack.$\endgroup$
– tbm0115Apr 5 '16 at 14:07

The most common issues most printers experience, such as delayering, warping, etc., are addressed completely differently based on the material you are working with. There are many examples of this, and I will attempt to go over some of the basic ones.

You will have extreme difficulty getting proper layer adhesion. Assuming you have a level, flat, semi-coarse (helps) surface for the first layer, the recommended heated bed temperature is 70C for PLA. With ABS, you will experience warping by the 5th layer at that temperature. ABS prefers 110C for a heated bed, and 80C for a heated chamber (personal experience for most reliable results).
Next issue is going to be delayering and stringing. There is no happy medium! Matter of fact, the number of issues even attempting this is almost too many to list. The quality will be complete garbage. On one hand you will have delayering, warping, and jamming of the ABS when set to PLA specs, and stringing, leaking, etc., when set to ABS specs.